Fuel injection systems



March 1969 H. EJACKSON FUEL INJECTION SYSTEMS I of 4 Sheet Filed Nov.28, 1966 March 11, 1969 H. E. JACKSON 3,431,900

FUEL INJECTION SYSTEMS Filed Nov. 28, 1966 March 11, 1969 H. E. JACKSONFUEL INJECTION SYSTEMS Sheet Filed Nov. 28, 1966 March 11, 1969 Filedliov. 28, 1966 FIG. 6.

H. E. JACKSON 3,431,900

FUEL INJECTION SYSTEMS United States Patent 54,793/65 US. (:1. 123-139 5Claims rm. cl. FtlZm 39/00 ABSTRACT OF THE DISCLOSURE A fuel injectionsystem for an internal combustion engine, in which fuel pressureincreases with increasing engine speed and in which, to provide properfuel supply to the fuel injector nozzles over the whole of the engineoperating speed range, the fuel supply path to the injector nozzles hasfirst and second parallel flow branches, connected directly to thenozzles by feed conduits, the flow paths defined by the feed conduitsand the nozzles including fixed flow equalising restrictors. In oneembodiment, an engine load responsive fuel fiow control valve connectsthe supply path and the first branch, and the second branch contains anengine load responsive fuel flow conload responsive valve) contains areference fiow restrictor the fuel pressure drop across which isindicative of fuel supply to the injector nozzles and'is used to controla flow control valve in the second branch to maintain that branch openonly at engine speeds below a preselected value. In a second embodiment,the supply branch contains an engine load responsive fuel flow con trolvalve located upstream of both the first and second branches. Both thefirst and second branches include fuel pressure responsive valves, thatin the first branch opening at a higher fuel pressure than that in thesecond branch. The second branch includes a reference flow restrictorand communicates with the first branch downstream of the fuel pressureValve in the first branch. At low engine speeds (when fuel pressure islow) the first branch is closed and the second branch is open. As enginespeed (and fuel pressure) increase, the back pressure across thereference fiow restrictor closes the second branch.

This invention relates to continuous fuel injection systerns in general,both those employing vented injector devices as well as those employingcompressed-air atomizing injector nozzles. More particularly, theinvention is concerned with fuel supply to the injector devices in suchsystems.

The invention is concerned with the recognised problem of ensuringadequate fuel supply to the injector devices at low engine speeds,including engine idling speeds, without supplying excessive fuel athigher engine speeds.

According to the present invention, a continuous fuel injection systemfor an internal combustion engine has a fuel supply conduit connected tofuel injector devices and including an engine drivable fuel pumpingdevice operable to pressurise fuel in dependence on engine speed, thefuelsupply conduit including first and second parallel flow branches,the supply conduit also including a fuel metering vave arrangementoperable in response to engine loading to supply fuel to the injectordevices via the first branch over the greater part of the engineoperating speed range above a selected relative-1y low engine operatingspeed, and the second branch containing a flow restrictor forming partof a fuel flow control device so operable that fuel passes through thesecond branch only over a range of engine speeds at the lower end of thespeed range and occupying a small proportion of the overall engine speedrange.

3,431,900 Patented Mar. 11, 1969 In a preferred embodiment, the fuelmetering valve device has a variable area orifice disposed in the firstbranch. In this embodiment the second branch includes a fixed flowrestrictor and a closure valve member operable to close the secondbranch at engine speeds higher than the small range of engine speeds atthe lower end of the overall speed range. In a system in which fuelsupply pressure is increased with increasing engine speed over the wholeof the operating speed range, the closure valve member can be operablyresponsive to fuel supply pressure such that it is closed by fuelpressures corre sponding to engine speeds above the selected enginespeed.

In another embodiment, in which fuel pressure in the fuel supply conduitis so controlled that during engine operation at speeds higher than theidling speed range, the fuel pressure equals a predetermined constantvalue and increases beyond that value with increasing engine speed, thefirst branch includes a first fuel pressure responsive valve memberopenable at the predetermined fuel pressure to pass fuel via the firstbranch to the injector devices. The second branch includes a relativelyhigh resistance fixed flow restrictor arrangement and a second fuelpressure responsive valve member openable at a pressure lower than thepredetermined fuel pressure to pass fuel through the second branch atengine speeds in the idling speed range, when no fuel passes through thefirst branch, the amount of fuel passing through the second branch, whenthe first branch is open, being zero or a negligible value due to therelatively high flow resistance of the flow restrictor arrangement inthe second branch.

In systems incorporating a fuel supply arrangement according to theinvention, it is preferred that the supply conduit is also connected viaa fixed (preferably adjustable), flow restrictor arrangement to a fuelreturn or bypass line. During operation of such a system, fuel from thesupply line passes partly to the injector devices and partly to thereturn or by-pass line, the flow proportions depending on the flowrestriction offered by the injector devices and the restriction offeredby the flow restrictor arrangement connecting the supply line to thebypass line.

By way of example, embodiments of the invention will be descibed ingreater detail with reference to the accomp'anying drawings, in which:

FIGS. 1 and 4 are schematic illustrations of two sys terns according tothe invention,

FIG. 2 shows a modification of part of FIG. 1,

FIG. 3 is a diagrammatic illustration of a component of FIG. 1,

FIG. 5 is a cross-section of a component of FIG. 4,

FIG. 6 is a section on the line VIVI in FIG. 5,

FIG. 7 is a section on the line VII-VII in FIG. 5, and

FIG. 8 is a front view of FIG. 5.

In FIG. 1, there is shown a low pressure continuous fuel injectionsystem for an internal combustion engine. The system has a fuel supplyconduit system including a supply line 1 including parallel branches 1Aand 1B connected by lines 2A and 2B to a chamber 3 which in turn isconnected to a distribution chamber 4 from which lines 5, containingflow equalising restrictors 6, lead to fuel injector devices 7 disposedin the inlet manifold structure of the engine such that the fuel spraydischarged from the injector devices is drawn into the engine cylinderswhen the inlet valves open. This disposition of the injector devices isillustrated, for example, in copending application No. 8,528/ 65.Down-stream of their connections to the chamber 3, the branches 1A and1B are connected via fixed adjustable flow restrictors 8A and SE to afuel b-y-pass line 9.

Fuel is supplied to the supply branch 1 from an engine drivenpressurising pump 10 operable to pressurise fuel in the supply line independence on engine operating speed so that as engine speed increases,so does the fuel supply pressure. The pump llti is fed by a priming pump11 that delivers fuel at a constant pressure determined by a reliefvalve 12, having a vent 17, a lift pump 13 supplying fuel to the primingpump from the fuel tank M of the engine via vapour separator 15. Theby-pass line 9 is connected back to the tank 14 via a relief valve 16having a vent 17, the vapour separator and a check valve 13.

In operation of the system, as so far described, fuel is pumped throughthe supply line It at a pressure dependent on engine speed, the flowfrom the supply line dividing between the injector devices 7 and theby-pass line 9 in a proportion dependent on the relation between theflow restrictors 6 and the flow restrictors 8A, 88. By suitable choiceof the flow resistances of these restrictors, circulation of fuel in thelines 1 and 9 can be maintained over the normal range of engine speedswhilst maintaining desired fuel supply to the injector devices.

The amount of fuel passing through the supply line it is determined byflow restrictors in the supply line branches 11A and 1B. The supply linebranch 1A contains a variable flow restrictor 20, the flow resistance ofwhich is controlled in response to engine loading (as determined, forexample, by engine inlet manifold vacuum or engine throttle opening) toincrease the fuel flow as the engine load increases. Whilst this controlis effective to meter an adequate fuel flow to the injector devices atengine speeds above the engine idling speed range, the engine can bestarved of fuel supply when the engine is idling with the variablerestrictor 20 closed due to the negligible engine load. If, at engineidling speeds, the restrictor 2th is arranged to be open sufficiently toensure adequate fuel supply to the injector devices, then at increasedcngine loads excess fuel is supplied to the injector devices, which isundesirable. The problem is solved in the system shown in FIG. 1 byprovision of a fixed restrictor 21 in the branch 1B of the supply line 1at a location upstream of the connection of the branch to the restrictor6B, and a valve member 22 engageable with a seating 23 disposeddownstream of the connection of the branch 18 to the restrictor 8B. Thevalve member 22 is urged towards an unseated position by a light spring24 and is carried by a plunger 25 exposed to fuel pressure in the supplyline branch llB upstream of the restrictor 21. At engine idling speeds,and low operating speeds when the variable restrictor 20 is closed oronly slightly open, the spring 24 is arranged to prevent the valvemember 22 being seated by fuel pressure in the branch 1B (which isdependent on engine speed) acting on the plunger 25. Thus, fuel can flowvia restrictor 21 past a non-return valve 26 to the distribution chamber4- and hence to the injector devices 7, the restrictor 21 offering aflow resistance such that there is adequate fuel flow to the injectorsunder these engine operating conditions.

As the engine speed increases, the unseating force for the spring 24 isovercome by the fuel pressure in the branch llB acting on the plunger 25so that any fuel flow through the restrictor 21 passes via restrictor SEto the bypass line 9. Fuel flow to the injector devices then is solelyvia the variable restrictor 20 in the branch 1A, the flow resistance ofwhich decreases with increasing engine load. Thus, fuel supply to theengine is metered by adjustment of fuel supply pressure in dependence onengine speed and adjustment of fuel flow in dependence on engineloading.

Under engine overrun conditions, i.e. high engine speed and enginethrottle closed (corresponding to negligible engine loading and highinlet manifold vacuum), the variable restrictor 249 is closed and thevalve member 22 is seated so that the injector devices receive no fuelsupply, which is the desired condition.

The injector devices 7 each have a housing 110 from which projects atube 111 at the end of which is an outlet orifice 112. A resilientdiaphragm 113 divides the housing into two chambers 114 and 115, theformer communicating with a feed line 5 and with the tube 111 and thelatter containing a light spring 116 bearing on the diaphragm and urginga. valve member 117 carried by the diaphragm towards a seated positionin the outlet orifice 112. The arrangement is designed such that inletmanifold vacuum does not interfere with fuel flow to the injectordevices, particularly under conditions of low engine speed (i.e. lowfuel pressure) and high inlet manifold vacuum (e.g. engine idlingcondition), the nozzles of the injector devices being disposed in theinlet manifold downstream of the throttle valve. Under these conditionsfuel flow through to injector outlet orifice 112 might be such that thechamber 114 became exposed to inlet manifold vacuum which wouldinterfere with fuel flow to the injector devices. However, when fuelflow falls to such a level, the spring H6 seats the needle 117 in theoutlet orifice until fuel pressure in the chamber 114 acting ondiaphragm 113 is sufiicient to unseat the needle 117.

Instead of connecting the lines 2A and 23 to a common chamber 3 which inturn is connected to a distribution chamber 4, each of the lines 2A and23 could be connected to separate distribution chambers 30 and 31 asshown in FIG. 2. From the chamber 3%, lines 32 containing non-returnvalves 33 communicate with the feed lines 5 to individual injectordevices 7, the feed lines 5 containing flow restrictors 6. The chamber31 also communicates via lines 34 containing flow restrictors 35 withthe feed lines 5 to the individual injector devices '7, the points ofconnection being upstream of the restrictors 6.

FIG. 3 shows, in section, a control assembly containing the flow controlcomponents in the supply line branches 3A and 1B. The assembly has ahousing 40 having a cylindrical chamber 41 containing the variablerestrictor 20. The restrictor includes a sleeve 42 having an aperture43. Rotatably disposed in the sleeve is a closely fitting valve member 4having a passage 45 extending partly along its length from one endthereof. An elongated transverse slot 46, having outwardly divergentwalls which, projected, define a V-section, is formed in the wall of thevalve member and communicates with the passage 45 and the aperture 43 inthe sleeve. A passage 47 leads from the aperture 4-3 to a first outletport 48.

A fuel inlet port 49 communicates via a passage 50 with the chamber 41and the open end of the valve member 44. A passage 51 leads from thepassage So to a chamber 52 which communicates via a small bore passage53 (forming the fixed restrictor ,1) in the closed end of plunger 25with the interior of the plunger. The plunger 25 carries the valvemember 22 engageable with the seating 23 which is provided at one end ofchamber 52. The spring 24, biases the plunger 25 to an unseatedposition. A passage communicating with the bore of the seating 23downstream of the non-return valve 26 leads to a second outlet port 54whilst a passage 55 leads to a return flow port, not shown.

In use of this control assembly in the system shown in FIG. 1, the inletport 49 is connected to the supply line 1, the passages 50 and 51forming the inlet sections of branches 1A and 1B. The first outlet port48 is connected to line 2A and to restrictor 8A, the second outlet port54 to the line 213 and the return flow port (not shown) to which thepassage 55 leads is connected to the restrictor 8B.

The valve member 44 of the variable restrictor 21 shown in FIG. 3extends, at its closed end, into a chamber 56 and is coupled by an arm57 to a roller 58 engaged by a cam 59 carried by a shaft 60 for rotationtherewith. The shaft 60 can be coupled to the engine throttle operatingmechanism so that as the throttle is opened, the cam 59 is rotated, thevalve member 44 also being rotated in a manner dependent on the camsurface of cam 59. As the valve member 44 rotates, the area of theV-slot 46 is registration with the aperture 43 increases therebyincreasing fuel flow to the port 48 as the throttle opening increases.

Instead of being coupled to the engine throttle opening mechanism by theshaft 60, the cam 59 could be coupled to a plunger movable to rotate thecam in response to engine inlet manifold vacuum so that decreasingmanifold vacuum causes increase in the fuel flow through the outlet port48.

The system illustrated in FIG. 4 differs from that shown in FIG. 1 intwo main respects. Firstly, the branch of the supply line 1 of thesystem shown in FIG. 4 includes a fixed fiow restrictor 71 for eachnozzle. In place of the variable flow restrictor shown in FIG. 1, thesystem shown in FIG. 4 has a variable flow restrictor 73 connected inthe supply line 1 upstream of the branches 1A and 1B. The variable flowrestrictor 73 can be of similar construction and operated in like mannerto the restrictor 20 shown in FIG. 3. Alternatively, it can beconstructed in the manner disclosed in respect of the metering valveshown in co-pending application No. 8,528/ 65. The second difference ofthe system shown in FIG. 4 as compared with that shown in FIG. 1, isthat the fuel flow in the supply line 1 has, under normal engineoperating conditions, a minimum pressure determined by a diaphragm valve74 connected in the supply line branch 1A whilst fuel flow through theby-pass line 9 has a like minimum pressure determined by the reliefvalve 16.

The branches 1A and 1B are connected to distribution chambers 4A and 4Bto which the injector devices 7 are connected by respective flow lines 5containing flow restrictors 6, in the manner described with reference toFIG. 1. A check valve in each connection to flow lines 5 prevents returnfiow to chamber 4A. The standing fuel pressure introduced by thediaphragm valve 74 is sutficient to prevent fuel vaporisation upstreamof the diaphragm valve 74 during all operating conditions and speeds ofthe engine. Downstream of the diaphragm valve 74, in the flow paths tothe injector devices, the standing pressure is not present but isre-introduced in the by-pass line 9 by the relief valve 16.

During engine operation at idling speeds when the fuel pressure in thesupply branch 1, determined by the engine driven pump 10, is less thanthat necessary to open the diaphragm valve 74, fuel passes to theinjector devices 7 through supply line branch 1B. This branch contains adiaphragm valve 75 that is opened at a fuel pressure sufficiently lowerthan that required to open the diaphragm valve 74, to ensure an adequatefuel supply to the injector devices under engine idling conditions, whenthe variable restrictor 73 in only partly open. Fuel flow through thediaphragm valve 75 passes to chamber 4B and through the restrictors 71to the injector feed lines 5.

As the engine speed increases above the idling speed range, thediaphragm valve 74 opens and fuel fiows through both branches 1A and IEto the injector devices until the back pressure across the restrictor 71(which has a higher flow resistance than that of restrictor 6) reducesfuel flow through the branch IE to a negligible value or to zero.

FIGS. 58 show a control assembly 80 containing the diaphragm valves 74and 75 and the flow restrictor 71. The control assembly 80 has an inletport 79 leading via passages 81 and 81' (forming parts of branches 1Aand 1B respectively) to annular chambers 82 and 82' forming parts of thediagragm valves 74 and 75 respectively. The chambers 82 and 82' areseparated from distribution chambers 30 and 31 by resilient diaphragms83 and 83 urged by springs 84 (adjustable by screws 85) towards seatedpositions on annular walls 86, 86', projecting into the chambers 82, 82,respectively, to define chambers 87 and 87. The diaphragms 83 and 83'have central apertures 88 and 88' so that when the diaphragms areunseated, fuel can flow from the chambers 82 and 82' via chambers 87 and87 and the apertures 88 and 88' in the fit 6 diaphragms 83 and 83 intothe distribution chambers 30 and 30'.

The distribution chamber 30 communicates via a passage with a chamber 89from which lead individual passages 90, each containing a non-returnvalve 91, to ports 92 (to which the lines 5 are connected). Thedistributor chamber 31 communicates 'via passages 94, each containing arestrictor in the form of a long fine tube 95, to the ports 92 intowhich the tubes 95 extend.

Downstream of the passages 81 and 81, the inlet port 79 communicateswith a chamber 96 containing an orifice disc 97 and an adjustable flowrestrictor 98. The restrictor 98 extends through the orifice disc 97 andhas a portion 99, the transverse cross-section of which varies along thelength of the restrictor. The flow restriction presented by the orificethus depends on the position of the variable area portion 99 relative tothe disc 97 which position can be adjusted by a screw 100, against whichthe restrictor 98 is held by a spring 101. An outlet port 102 leads fromthe chamber 96, downstream of the orifice disc 97, and in use of theassembly is connected to the by-pass line 9 in FIG. 4, the variable areaorifice disc 97 forming the flow restrictor 8.

I claim:

1. A continuous fuel injection system for an internal combustion engine,comprising in combination:

(A) a fuel circulation path including a fuel supply conduit and a fuelreturn conduit, the fuel supply conduit having first and second parallelflow branches,

(B) feed conduits connecting said first and second branches directly toeach one of a plurality of fuel injector devices each having a fueloutlet orifice,

(C) a respective fixed flow equalising restrictor in each of the fuelflow paths defined by the said feed conduits and the injector devicesthe said fuel return conduit being connected to said first branchdownstream of the connection of said first branch to the injectordevices and being connected to said second branch upstream of theconnection of said second branch to the injector devices,

(D) an engine driven fuel pressurising device con nected in said fuelsupply conduit upstream of said first and second branches and operableto increase fuel pressure with increasing engine speed,

(E) a reference fixed flow restrictor in the said second branch upstreamof the connection to the said return conduit,

(F) a fuel pressure-responsive valve device in said second branchdownstream of the connection to the return conduit and means biasingsaid fuel pressure-responsive valve device to an open position, saidfuel pressure-responsive valve device being exposed to the fuel pressuredrop across said reference restrictor in the second branch to close thesecond branch in response to a fuel pressure drop corresponding toengine speeds greater than a predetermined value, and

(G) engine load responsive fuel flow control valve means connected insaid supply conduit downstream of said fuel pressurising device forsupplying fuel to the injector devices via said first branch independence on engine loading at least at engine speeds greater than thesaid predetermined value.

2. A system according to claim 1, wherein said fuel flow control valvemeans is connected in the said first branch of the supply conduit forsupplying fuel to the injector devices in dependence on engine loadingat substantially all engine speeds.

3. A system according to claim 2, wherein said fuel flow control valvemeans includes a rotary valve member and engine load responsive meanscoupled to said valve member for rotating said valve member toincreasingly open said first branch with increasing engine loading, andwherein said fuel flow control valve means and said fuelpressure-responsive valve device are contained in a common housing, afirst passage in said housing defining the first branch of the supplyconduit and containing the rotary valve member, a second passage in saidhousing defining the second branch of the supply conduit andcommunicating with the first passage upstream of the rotary valvemember, said second passage including a chamber defining a valveseating, a closure valve member engageable with said seating to closesaid second passage and means resiliently biasing said closure valvemember towards an unseated position, a plunger in said chamber carryingsaid closure valve member, and a passageway extending through theplunger defining the said reference fixed flow restrictor in the secondbranch whereby the pressure differential due to fuel flow through saidpassageway urges said plunger to move the closure valve member towards aseated position against said resilient bias.

4. A continuous fuel injection system for an internal combustion engine,comprising in combination:

(A) a fuel circulation path including a fuel supply conduit and a fuelreturn conduit, the said supply conudit having first and second parallelflow branches,

(B) feed conduits conecting said first and second branches directly toeach one of a plurality of fuel injector devices,

(C) a respective fixed flow equalising restrictor in each of the fuelflow paths defined by the said feed conduits and the injector devices,the said fuel return conduit being connected to said first branchdownstream of the connection of said first branch to the injectordevices,

(D) an engine driven fuel pressurising device connected in said fuelsupply conduit upstream of said first and second branches and operableto increase fuel pressure with increasing engine speed,

(E) a low fuel-pressure-responsive valve device in said second branchand means biasing said low fuelpressure-responsive valve device to aclosed position, fuel pressure in the second branch at engine speedsless than a predetermined value acting on said low fuel-pressureresponsive valve device to open said second branch and permit passage offuel to the injector devices,

(F) a reference fixed flow restrictor in the second branch downstream ofthe low fuel-pressure-respont3 sive valve device, the downstream end ofsaid reference flow restrictor being connected to said first branchdownstream of the connection of the branch to said return conduit, and(G) engine load responsive fuel flow control valve means connected insaid supply conduit downstream of said fuel pressurising device forsupplying fuel to the injector devices via said first branch independence on engine loading at least at engine speeds greater than thesaid predetermined value, the said reference flow restrictor in saidsecond branch having flow resistance such that pressure in said secondbranch upstream of said low fuel-pressure-responsive device acts on saidlow fuel-pressure-responsive device at engine speeds greater than thesaid predetermined value to close said second branch. 5. A systemaccording to claim 4, wherein said flow control valve means is connectedin the supply conduit upstream of the first and second branches forsupplying fuel to said first and second branches in dependence on engineloading at substantially all engine speeds, and including a highfuel-pressure-responsive valve device in said first branch and meansbiasing said high pressureresponsive valve device to a closed position,fuel pressure in said first branch at engine speeds greater than thesaid predetermined value acting on said high fuel-pressure-responsivevalve device to open the first branch and permit passage of fuel to theinjector devices.

References Cited UNITED STATES PATENTS 2,656,848 10/1953 Noon et a1123-119 XR 2,924,206 2/1960 Groves 123-43917 2,940,435 6/1960 Nemec etal. 123139 3,019,603 2/1962 Kreutzer 39.28 3,036,564 5/1962 Guiot123140.3 3,285,233 11/1966 Jackson 123139.17 3,330,300 7/1967 Jackson137614.14

LAURENCE M. GOODRIDGE, Primary Examiner.

US. Cl. X.R. 123119, 140

